Type 2 diabetics have to fight urge to overeat

CORPUS CHRISTI - The basic principle of weight loss is to burn up more calories than you consume. How can such a simple idea be so difficult to apply? Recent studies of brain function are starting to provide some startling answers.

In non-obese people, the drive to eat high calorie foods and drinks is strongly influenced by blood sugar levels. If blood sugar levels fall, the areas of the brain responsible for seeking out and enjoying food are switched on. Once blood sugar levels start to increase after a meal, the areas of the brain that are involved with reasoning and logic increase their activity and block down those areas of the brain that induced earlier feelings of desire to eat.

To have blood sugar play such a powerful role in how we eat should not be surprising. After all, sugar is the main energy source for the body. If sugar levels are drifting down, there needs to be some system in place to motivate the person to seek out high energy foods to quickly correct the deficit.

The two areas of the brain that control this give and take effect are the hypothalamus and prefrontal cortex. Desire, motivation and reward are the domain of the hypothalamus. Logic and reasoning are under the direction of the prefrontal cortex.

When researchers examined the brain function of non-obese and obese adults, they found that obese people did not switch off the reward system in the hypothalamus after eating, which is how brains of non-obese people are supposed to operate. In other words, there was a persistent emotional reward for eating high calorie foods that wasn't present in lean people.

When the blood sugar level of a lean person is stable and in a normal range, the prefrontal cortex is king. While the thought of food sounds enticing, that part of the brain is able to control the urge to eat through reason and logic. When it is less active, the more emotional centers located in the hypothalamus take charge.

Data examining the size of the prefrontal cortex in the brains of people with Type 2 diabetes suggests that theirs are smaller. If smaller size equals less function, this could be a disturbing combination, since the ability to resist the feelings and urges of reward and desire produced by the hypothalamus might be reduced, leading to overeating and obesity.

Viewing images of food can trigger an imbalance in desire and restraint. This may explain the power of modern advertising to drive some to overeat.

We like to think that we have total control over our choices, but in reality we don't. And obese people may be less well equipped to fight the sensory cues that prompt us to seek out high calorie foods and drinks.

These new findings highlight the need to develop practical tools to reduce the risk of loss of control over one's eating behaviors. Keeping large amounts of high calorie foods out of the house and avoiding visual food cues are good starts. Perhaps simply being aware that judgment and self-control might be harder in obese people could be used to redirect the urge to keep eating after a meal. Eating smaller portions and more frequent meals are thought to reduce the swings in blood sugar levels that might make this problem worse.